Berry, R. Albert, author
Md. Johns Hopkins University Press , 1979
Buku Teks
Artikel Jurnal
Hewings, Martin, author
Cambridge University Press , 2004
Buku Teks
edited by Murray Moo-Young, Campbell W. Robinson and John A. Howell
Pergamon Press, 1985
Buku Teks
Hale, Tammy J., author
Delmar, 2011
Buku Teks